Migrate `rawshift-core` to adopt `gamut-core` primitives

[justin13888]

rawshift is currently MPL-2.0 code itself. Goal is to standardize on permissively-licensed core primitives so it can be integrated more seamlessly with other libraries that share gamut-core's color, format, math primitives

https://github.com/justin13888/gamut/tree/master/crates/gamut-core

[justin13888]

Need to also make clear the relationship between rawshift and gamut. rawshift guarantees functionality for specific devices while gamut implements based on standards-first. Not all functionality in rawshift is provided by any particular library (e.g. gamut).

[justin13888]

Superseded by the v1 tracking graph: this work is now scoped in #18 (rawshift-core: gamut re-exports, keep sensor types) under the epic #38, with the full type-by-type disposition in docs/V1_DESIGN.md. Suggest closing in favor of #18.

[justin13888]

Closing as superseded by #18, delivered in #42. The metadata/ICC carve-out was handled by #19/#44; remaining v1 work is tracked by #38.